The present invention relates generally to a low oil warning system, and more particularly, to an apparatus and method to monitor oil pressure and other engine parameters in a two-stroke fuel injected engine.
Typically, two-stroke outboard marine engines do not have a separate oiling system. That is, these prior art engines require pre-mixing lubricant and fuel so that the lubricant dissolves in the fuel to lubricate the engine. This requires consistent, accurate measuring and agitation of the mixture. There are many disadvantages to the prior art system of pre-mixing lubricant and fuel. For example, since various two-stroke engines require different mix concentrations, and many outboard marine engine owners also own other two-stroke engine equipment, such as various lawn and garden equipment, snowmobiles, and ATVs, they may need to store several different concentrations of oil/fuel mixtures. This is not only an aggravation to the owner, but is also problematic if the containers become mixed up and the owner uses the wrong concentration for a particular two-stroke engine. While this is not catastrophic, if run over time with the wrong concentration, a two-stroke engine can wear excessively.
The present invention is for use in a unique lubrication system for two-stroke engines. Such a lubrication system must provide lubrication to each cylinder of the engine and provide lubrication to the fuel system to properly lubricate the fuel metering and injection system from an oil reservoir.
Unlike four-stroke engines, which are designed to re-circulate oil for lubrication and not consume oil, a two-stroke engine, by its nature, consumes oil during use. An oil injection system for a two-stroke engine is typically designed to pump just enough oil as is needed for lubrication and then it is consumed. Without feedback however, problems can occur in such metering systems. For example, engine temperature and ambient temperature can affect lubricant viscosity resulting in a need to change the rate of oil delivery. Also, certain operating conditions require more or less oil. Therefore, it would be advantageous to have an oil pressure monitoring system that continuously monitors oil pressure and consistently maintains a sufficient oil supply to the two-stroke engine. It would also be advantageous if the oil pressure monitoring system regulated the engine to reduce engine damage if sufficient oil cannot be supplied to the engine.
The present invention provides an oil delivery system for a fuel injected engine that continuously monitors oil pressure and attempts to consistently maintain an oil supply to the two-stroke engine by adjusting a duty cycle of an oil injection solenoid solving the aforementioned concerns.
The present invention provides a system and method to regulate the amount of oil delivered to the cylinders of the two-stroke internal combustion engine. The invention includes an oiling system for distributing oil throughout the internal combustion engine. The oiling system includes a pressure sensor connected between an oil injector and the internal combustion engine, which senses oil pressure and produces an oil pressure indicative signal to an electronic control unit (ECU). The ECU receives and monitors the oil pressure indicative signal and is configured to modify an oil injection signal delivered by the ECU to the oil injector.
In accordance with one aspect of the invention, an oil monitoring system for a two-stroke engine is provided. The system includes an oil system having an oil inlet, an oil outlet, and an electronic oil injector therebetween. The system also includes a pressure sensor connected to the oil system downstream of the electronic oil injector that is configured to detect oil pressure in the two-stroke engine. An ECU is also provided, wherein the ECU is in communication with the pressure sensor, the electronic oil injector, and an optional low oil warning system. The ECU is programmed to modify a duty cycle of the electronic oil injector upon the ECU receiving an oil pressure indicative signal indicating low oil pressure from the pressure sensor. If a desired oil pressure cannot be obtained, the ECU is further programmed to limit engine operation and activate the warning system so as to prevent a catastrophic engine failure, but allow the operator to use their judgment in operating the engine to travel to a safe harbor.
In accordance with one aspect of the present invention, an outboard motor is disclosed that includes an internal combustion engine having an oiling system to distribute oil throughout the internal combustion engine. The outboard motor also includes a water propulsion unit in operable association with the internal combustion engine to propel the outboard motor. The engine includes at least one oil injector connected to the oiling system to cause oil delivery through the oiling system. A pressure sensor is connected to the oiling system between the at least one oil injector and the engine to sense oil pressure downstream of the at least one oil injector and produce an oil pressure indicative signal in response thereto. The outboard motor also has an ECU connected to deliver a modulated signal to the at least one oil injector. The ECU is also connected to the pressure sensor to receive the oil pressure indicative signal. The ECU is configured to monitor the oil pressure indicative signal and modify the modulated signal in response thereto to regulate oil delivery through the internal combustion engine.
In accordance with another aspect of the present invention, a method of detecting a low oil pressure condition in a two-stroke engine includes the step of detecting oil pressure in a two-stroke fuel injected engine and determining if the detected oil pressure is within a given range for a given set of engine operating parameters, and if not, modifying a duty cycle of oil injection into the two-stroke engine. The method also includes the step of monitoring the duty cycle of oil injection and comparing the modified duty cycle to a range of duty cycle limits. The method also includes the step of limiting engine operation if the modified duty cycle is outside the range of duty cycle limits, and if not, repeating the aforementioned steps.
In accordance with yet another aspect of the present invention, an oil monitoring system for a two-stroke engine includes a means for injecting oil into a two-stroke engine, and a means for determining if the detected oil pressure is within a given range for a given set of engine parameters. Additionally, the oil monitoring system has a means for modifying the oil injected into the two-stroke engine to maintain the oil pressure within the range for the given set of engine parameters and if the oil pressure cannot be so adjusted, limiting engine operation.
Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings.